Doug and Skeeter are best friends who live in the town of Bluffington. They are both fascinated by the legend of a monster that lives in Lucky Duck Lake and decide to set out on an adventure to find it. They are accompanied by their friends, Patti and Porkchop.
As they search for the monster, they come across various clues and encounter several obstacles. At one point, they stumble upon a hidden underground cave where they are chased by a group of bats. They also run into the school bully, Roger, who tries to stop them from finding the monster.
Just as they are about to give up, a mysterious old man tells them that the monster is real and has been guarding a secret treasure for centuries. This news ignites their determination, and they continue their search with renewed vigor.
Finally, they come face to face with the monster, which turns out to be a gentle creature who has been protecting the treasure from outsiders. The treasure is revealed to be a collection of old toys and games that the monster has been hoarding for years.
In the end, the group learns a valuable lesson about the true meaning of treasure, which is not material wealth but the love and friendship they share. They return home, triumphant from their adventure, with a newfound appreciation for each other and the world around them.